Stereoscopic x-ray apparatus.



No. 688,458. Patented Dec. 10, l90l.

' E. W. cALDWELL.

STEREOSC" 1C X-RAY APPARATUS.

(Application filed Sept. 27, 1901.) (No Model.) 3 Sheets-Shoat l.

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No. 688,458. Patented Doc. ID, l90l. E. W. CALDWELL.

STEBEDSCOPIC X-RAY APPARATUS.

(Application filed Sept. 27, 1901.) (No Model.) 3 Shaats$haat 2.

No. 688,458. Patented Dec. l0, l90l. E. W. CALDWELL.

STEREOSCOPIC X-RAY APPARATUS.

(Application filed Sept. 27, 1901.) (No Model.) 3 Sheets-Sheet 3.

'/ III/I/I/Il/I A I r I Wl'in asses- I mfilnmzior W TNE NORRIS FETJIS co. PHOYG-LITNQ, vusummou, D. c

UNITED STATES PATENT OFFICE.

EUGENE W. CALDVELL, OF NEW YORK, N. Y.

STEREOSCOPIC X-RAY APPARATUS.

SPECIFICATION forming part of Letters Patent 0. 688,458, dated December 10, 1901. Application filed September 27, 1901. Serial No. 76,763. (No model.)

To ctZZ whom it may concern.-

Be itk'nown that I, EUGENE W. CALDWELL, a citizen of the United States, and a resident of New York, borough of Manhattan, county and State of New York, have invented certain new and useful Improvements in Stereoscopic X-Ray Apparatus, of which the following is a specification, taken in connection with the accompanying drawings, which form a part of the same.

This invention relates to stereoscopic X-ray apparatus, and is especially adapted to give stereoscopic images in a fluoroscope, so that the fluoroscopic image of an object as seen by this apparatus indicates correctly the solidicity of an object corresponding to what is seen in normal vision.

In the accompanying drawings, in which the same reference character refers to similar parts in the various views, Figure 1 is a diagrammatic plan view of my apparatus, the fiuoroscope being shown on a larger scale. Fig. 2 is a vertical sectional view through the fluoroscope. Fig. 3 is a transverse section of the same. Figs. 4 and 5 are diagrammatic views indicating the field-windings which I use. Figs. 6, '7, and 8 show another construction.

The X-ray tube A, preferably of glass, is formed of an elliptical body A, having the elongated ends A secured to it on either side. In each of these ends is mounted the electrode-terminals A and A these terminals being supported in the glass pillars, as indicated, and on the inner ends of these terminals are concave electrodes A and A, respectively, formed of aluminium and of usual construction. In the center of the body is supported the anticathode-terminal A in a similar manner, and connected with this terminal are the two anticathodes A and A formed of platinum and preferably plane surfaces, as indicated. They are situated at the foci of the concave electrodes, and these foci are separated a considerable distance from each other, as indicated in Fig. 1, so that the radiation of the X-rays takes place from sub stantially a point on the anticathodes A and A My X-ray tube is therefore a doublefocus tube in which the foci are separated to give alternately radiation from two separated art.

points. The foci are preferably separated about three inches in practice.

The X-ray tube is formed with regulators A on each of the end portions, these regulators being of tubular construction and having a regulator-terminal A secured to the same and com municatiug with a mass of regulating-salt A -such as, for instance, potassium hydrate. This salt, as is well known in this art, is adapted to give off a suitable vapor upon the passage of an electrical discharge through the regulating-tube, so that the dc gree of vacuum in the tube is regulated by this means.

F indicates a source of electrical energy. The commutator F at one end receives, as indicated, a constant current, and this electricity passing through the rotary converter or motor-generator is transformed into two alternating currents forming a two-phase system,which are taken oif the collector-rings F, F F and F", respectively. The primary D of the induction-coil D is connected with one of these alternating circuits, the liquid-interrupter E being in series with the primary. This liquid-interrupter is of the construction disclosed in my Patent No. 677,498, of July 2, 1901. The liquid E, which is contained in a vessel E, has a very small cross-section at the point E where it communicates with the portion of the liquid within the cup E so that the current in passing from the electrode E within the cup to the external electrode E vaporizes the reduced section of this liq-' uid, breaking the circuit and giving a rapid rate of interruption, as is well known in this In this way an interrupted alternating current passes through the primary D of the induction-coil, since the direction of the discontinuous current varies with the direction of the alternating current in the circuit F P In the secondary D of the induction-coilthe direction of the high-potential electricity varies correspondingly, so that the electrical discharges passing between the electrodes A and A are discontinuous and vary in direction with the alternating current in the primary circuit. The double-focus tube, therefore, gives a source of X-rays which alternately radiate from the separated foci on the anticathodes A and A in accord with the variations in the direction of the current in the alternating circuit F F The connections for the regulation-circuits are indicated in dotted lines in Fig. 1, the regulator-terminal A on the right end of the tube being connected through the adjustable air-gap D to the secondary circuit which supplies the electrode-terminal A and the regulator-terminal A on the left end of the tube being connected through the adjustable airgap D", which is connected with the terminal A as indicated. The length of the air-gaps D and D' may be varied according to the necessities of the regulation, and in this wayit will be seen that a variable electrical discharge will take place at any instant between the electrode A and the adjacent regulatorterminal and between the electrode A and its adjacent electrode-terminal A In this way the evolution of vapor from the regulators is secured in the quantity desired to properly reduce the degree of vacuum within the tube. Underordinary conditions of working the regulator-circuits are used only to the extent required to secure the proper vacuum within the tube and then are usually disconnected.

The fiuoroscope B comprises a cylindrical body B", upon which the cover-plate B is secured by screws, as shown, to form an interior chamber. The opening B formed in the side of the chamber communicates with the interior of the conical funnel B to the outer end of which is secured the fluorescent screen 13. This screen is formed in a well-known manner of paper or an equivalent substance, upon which are deposited crystals of a fluorescent substance, such as barium platinum cyanid. The opening 13 formed in the opposite side of the body communicates with the shield B to exclude extraneous light from the eye when looking through the fluoroscope. Ifdesired, this shield may be lined at its outer edge with any suitable flexible material such as, for instance, fur. The plate H, preferably of ebonite or other non-metallic material, is secured within the cylindical body of the fluoroscope, and the shutter K, secured rigidly to the pivot K, is mounted to rotate on this frame, the pivot having one bearing in the frame and also having abearingin the bar H rigidly secured to the frame. The supporting-pillars H are also secured to the frame, and the guide-grooves H are formed in these pillars and also in the pillars supporting the bar H In these grooves is mounted the field-plate G to Which the handle G8 is secured, this handle projecting, as indicated in Figs. 2 and 3, through a suitable slot B in the side of the fluoroscope-body, so that by this means the field-plate may be adjusted through a considerable angle. To this handle G is secured the shield G of circular form, fitting within the chamber, so as to exclude light from the opening 13*. The fieldring G preferably of laminated soft iron, which is wound with a number of coils G4 and G twelve coils being shown, is secured to the field-plate by suitable bolts, (indicated,) so that the field is adjustably mounted about the shutter K.

I have indicated the field as being wound with twelve coils connected in the usualtwophase arrangement, (indicated in Fig. 4,) the binding-posts G, G G and G being connected with the circuits F, F F and F, respectively, to produce a six-pole rotating field, as is well known in this art. The poles of thislfield rotate continually about the fieldcore, the speed of rotation varying with the periodicity of the alternating currents sent through the coils. I find that with the ordinary commercial practice this winding gives about the correct speed of rotation, although the numberof coils and the consequentspeed of rotation may be varied as desired. The exact form of winding is not important and may be varied considerably from what I have indicated. In Fig. 5 I indicate diagrammatically a common form of split-phase winding. The coils G and G, formed of ditferentmaterial, are joined in parallel to the two terminals G G and in this instance the terminals would be connected with a source of sin gle-phase alternating current-for instance, to the circuit F F As indicated in Fig. 2, the shutter K is formed with three curved apertures K equally spaced about its axis, and also with three other smaller openings in its edge, forming six projecting pole-pieces K equally spaced about the shutter. This shutter is made of soft iron, so that the rotating poles of the field will act upon the pole-pieces to start rotation of the shutter, and finally, as is well known in this art, will rotate the shutter as a synchronous motor at the same speed of rotation as the rotating poles of the field. It will also be apparent, that the shutter will make one-third of a revolution for every complete alternation of the current passing through the field-coils.

The two sight-holes I l and H (indicated in Figs. 1 and 2) are formed in the frame-plate, and, as will be best seen from Fig. 2, these sight-holes are arranged to cooperate with the openings K in the shutter, so that when one of these sight-holes-JI, for instanceis opened the other will be completely closed by the shutter, the opaque pieces K preferably of non-magnetic material, being secured to the shutter between the poles K of the same. After the shutter has revolved a sixth of a revolution from the position indicated in Fig. 2 the sighthole II will be opened and the sight-hole II will be closed. After another sixth of a revolution the position of the shutter will correspond to that indicated in Fig. 2, so that for every third of a revolution of the shutter from the position indicated in Fig. 2 there is a double reversal of the sight-hole through which vision occurs in the same time that acomplete alternation of the current in the field-coils takes place;

which gives a more powerful radiation oi X- rays. The two foci of this tube are preferably made about three inches apart,although the distance between the foci may be varied as desired to suit the requirements of different classes of work. If desired, either of these forms of X-ray tube may be employed 7 as a single-focus tube by shutting off the X- rays from one of the anticathodes.

It will be apparent to those skilled in this art that numerous variations may be made in my apparatus. Ihe relative proportions of the apparatus need not be the same as indicated. Indeed, in practice I prefer to employ a double-focus X-ray tube in which the two foci are situated at about the same dis tance apart as the two eyes of the observer, or, indeed, the foci may be considerably farther apart. Parts of my apparatus, furthermore, may be used without employing all of the same, and it is possible to use my improved form of fluoroscope in connection with two single-focus tubes, although by using a double-focus tube of this type it is not necessary to overcome the great practical difliculties to variation of vacuum in the two tubes. Many other variations in my apparatus may be employed without departing from the spirit of my invention. I do not therefore wish to be limited to the disclosure which I have made; but

What I desire to secure by Letters Patent is set forth in the appended claims:

1. In a stereoscopic X-ray apparatus, two alternating circuits forming a two-phase system, a liquid-interrupter and an inductioncoil connected in series to one alternating circuit, a double-focus vacuum-tube comprising two concave electrodes connected to said induction-coil, and two separated anticathodes at the foci of said electrodes, a movable fluoroscope comprising a fluorescent screen, two sight-holes, a rotating shutter having sightopenings therein, a two-phase field about said shutter connected to said two-phase alternat ing circuits and means to adjust the position of said field angularly with respect to said sight-holes.

2. In a stereoscopic X-ray apparatus, a vacuum tube provided with a pair of concave electrodes at either end, a pair of separated anticathodes upon which the concave electrodes focus, asource of interrupted alternating electricity connected to said electrodes, a fiuoroscope comprising a fluorescent screen and a revolving shutter forming the rotating part of a synchronous two-phase motor, a twophase field about said shutter connected to a source of electricity of the same periodicity as the source of electricity to which the electrodes are connected and sight-holes adjacent said shutter.

3. In a stereoscopic X-ray apparatus,a double-focus vacuum-tube having separated foci connected to a source of electricity to give alternating radiation of X-rays from the two foci of the tube and a movable fluoroscope assess comprising a fluorescent screen, two sight holes and means to cause an alternation of vision between the two sight-holes synchronous with the alternation of radiation from the two foci of the tube.

4. In a stereoscopic X-ray apparatus, a denble-focus vacuum-tube having separated foci, means connected to a source of electricity to produce an alternation of radiation of X-rays between the two foei of the tube, a fluorescent screen and means to cause an alternation of vision of the screen synchronous with the alternation of radiation from the two foci of the tube.

5. In a stereoscopic X-ray apparatus to give a stereoscopic image of an object, a vacuumtube comprising two separated sources of al ternating radiation of X-rays and means on the opposite side of said object from said tube to cause an alternation of vision of such radiation synchronous with the alternation of such radiation, said means being bodily movable with respect to said object.

6. In a stereoscopic X-ray apparatus to give a stereoscopic image of an object, means to produce an alternating radiation of X-rays from two separated sources and a fluoroscope placed on the other side of said object from said means and comprising a fluorescent screen and means to cause an alternation of Vision synchronous with the alternation of said radiation, said fluoroscope being bodily movable with respect to said object.

'7. In a stereoscopic X-ray apparatus to give a stereoscopic image of an object, a vacuum tube to give an alternating radiation of X- rays from two separated sources and a fluoroscope placed on the opposite side of said object from said vacuum-tube and comprising a fluorescent screen and means to cause an alternation of vision of said screen synchronous with the alternation of said radiation, said fluoroscope being bodily movable with relation to said object.

8. In a stereoscopic X-ray apparatus, a movable fluoroscope comprising a body portion, a fluorescent screen secured to said body portion, a shield secured to said body portion opposite said screen, a frame-plate secured to said body portion, there being sight-holes formed in said frame-plate to allow vision of said screen, a rotating shutter having sightopenings therein to allow alternate vision of said screen through said sight-holes, a fieldplate mounted on said frame-plate and angularly adjustable about said shutter, a twophase alternating field secured to said fieldplate to form in connection with said shutter a self-starting synchronous motor.

9. In a stereoscopic X ray apparatus, a movable fiuoroscope comprising a body portion, a fluorescent screen anda shield secured on opposite sides of said body portion,a frameplate secured to said body portion having sight-holes formed therein to allow vision of said screen, a rotary shutter mounted adjacent said sight-holes, there being sight-opcnor, in other words, I might say that the alternations of vision between the two eyes is synchronous with the alternations of the alternating current.

Referring to Fig. 1, the object 0 being between the tube and the fluoroscope-screen indicated, two X-ray images of this object O and C are produced on the fluoroscopescreen by X-rays proceeding from the anticathodes A and A respectively. If we assume that the position of the eyes of an observer looking into the fiuoroscope is at K and K the image 0, if seen by the eye K", is projected along the line indicated through the object C, while the image C if seen by the eye K is projected along the line indicated through the object O. The simultaneous effect of the vision of the two images, as indicated, would therefore give a stereoscopic image at the place occupied by the object C. The rotating shutter accomplishes this result, since, as is indicated in Fig. 1, the shutter being in the same position indicated in Fig. 2, vision occurs only by the eye K at this time. At this instant, however, the'X-rays are being radiated only from the focus on the anticathode A, so that the object 0 produces at this instant only the X-ray image 0. After one-half a complete alternation the X-rays are radiated only from the focus on the anticathode A thus producing the image 0 At this instant the shutter K having revolved through one-sixth of a revolution has closed the sight-hole H and opened the sight-hole H to allow vision of the image 0 by the eye K The rapid succession of the images produces a blending of image, so that the effect produced is that of continuous vision by each eye of the image seen by that eye, thus approaching very closely normal binocular vision of an object in its proper shape and space relation.

If the field-plate is moved by the handle G through a sixth of a revolution into the position indicated by dotted lines representing the handle in Fig. 2, it will be evident that the shutter K will be displaced in all its movements through one-sixth of a revolution, so that the sight-hole II will be open, allowing vision by the eye K while the image 0 is produced, and the sight-hole II will be opened, allowing vision by the eye K while the image C is being produced. In this way pseudo stereoscopic vision will result, since an image of the object O is thus formed inside the fluoroscope and substantially symmetrical to 0 inside of the screen. This adjustment may of course be made while the apparatus is in normal operation, and by a quick change it is possible to very accurately estimate the relative position of objects. It will of course be apparent that any object in a plane perpendicular to the axis of the apparatus passing through the object C will produce a stereoscopic image which will lie in the same plane as the object, although only in a single case will the image and object coinanticathode L cide. If the object is not in the same plane as the object O, the stereoscopic image of the object will not be in the same perpendicular plane as the object itself. In order to secure, therefore, the proper relative position of the object, the tube, and the iluoroscope, I prefer to make the fluroscope movable and provide it with a handle B of any desired shape, by which its position may be readily varied during the operation of the device. In this way much more perfect results may be obtained. WVhile I have explained the action of my apparatus in the vision of a single simple object C, it will be apparent that the same action takes place when a compound object is viewed, and the image of such an object will be in stereoscopic relief, since of course every compound object is composed of simple elements.

In Fig. 6 is shown another form of vacuumtube L, in which the elliptical body portion L is provided with end portions at either side of the tube, and in these end portions are mounted the terminals L and L respectively. Upon the terminal L is mounted the concave electrode L which is secured to the supporting-wires L This electrode is pro- Vided with a central aperture L. Secured to the rear side of this electrode is the pocketshaped anticathode L riveted or otherwise rigidly secured to the electrode. The similar electrode L is secured to the terminal L by the three supporting-wires L and this electrode is provided with the central aperture L, and the anticathode L is similarly mounted on the rear of this electrode. The form of the anticathode and its mounting upon the electrode may be readily seen from Fig. 7, which is a rear view of one of the electrodes. This tube, which may, if desired, be provided with regulators, is connected similarly to my other form of tube, as is indicated in Fig. 8, the two terminals L and L being connected to the secondary of the induction-coil D, so that an interrupted electric discharge alternating in direction passes between the electrodes. The fiuoroscope B is connected,as has been previously described, to the two-phase circuits and is operated to view the object O, as has already been described. With this construction of tube, which is preferable for many reasons, the cathode stream being omitted from the electrode L which at that instant is the cathode, is repelled from the cathode under the electrical influence of the cathode and is also attracted by the neighboring anode L The cathode stream focuses upon the anticathode I after passing through the aperture L in electrode L so that the X-rays produced on the anticathode are all radiated from substantially a single point upon it, the focus of the electrode L". In a similar manner the electrode L when it is a cathode produces X- rays which are radiated from its focus on the In this way a much more compact form of tube is secured and one ings formed in said shutter to alternately allow vision through said sight-holes, said sh utter being formed of iron and having projecting pole-pieces thereon, a synchronous field about said shutter and means to adjust the position of said field angularly with respect to said sight-holes.

10. In a stereoscopic X-ray apparatus, a vacuum-tube comprising; a body portion, end portions secured to the opposite sides of said body portion, electrode-terminals secured in said end portions,concave focusing-electrodes secured to said terminals and symmetrical about the axis of said tube, and inclined anticathodes mounted in said tube at the foci of said electrodes and substantially on the axis of said tube to give separated sources of X- rays which radiate in the same direction and substantially perpendicular to the axis of said tube.

11. In a stereoscopic X-ray apparatus, a vacuum-tube comprisinga body portion, end portions at opposite sides of said body portion, electrode-terminals secured to said end portions, concave electrodes mounted on said terminals facing each other and separated anticathodes-mounted in said tube at the foci of said electrodes to give separated sources of X-rays which radiate in substantially the same direction.

12. In a stereoscopic X-ray apparatus, a vacuum-tube comprising a body portion, concave electrodes mounted at either end of said body portion, separated anticathodes mounted at the foci of said electrodes, the said fooi being substantially three inches apart to give separated sources of X-rays which radiate in substantially the same direction.

13. In a stereoscopic X-ray apparatus, a

vacuum-tube comprising concave electrodes and separated anticathodes at the foci of said electrodes to give separated sources of X-rays which radiate in substantially the same direction.

14:. In a stereoscopic X-ray apparatus, a vacuum-tube comprising a body portion, concave electrodes formed with a central aperture mounted at either end of said body portion and symmetrical about the axis of said tube and inclined anticathodes secured to said electrodes behind said apertures therein to give separated sources of X-rays.

15. In a stereoscopic X-ray apparatus, a vac u u n1-tube comprising a body portion, concave electrodes formed with apertures therein mounted opposite to each other in said body portion and anticathodes secured to said electrodes behind said apertures to give separated sources of X-rays, said a'nticathodes being substantially at the foci of the opposite electrodes.

16. In a stereoscopic X-ray apparatus, a vacuum-tube comprising concave electrodes and anticathodes secured to each one of said electrodes and substantially at the foci of another of said electrodes to give separated sources of X-rays.

17. In a stereoscopic X-ray apparatus, a vacuum-tube comprising opposing concave electrodes and anticathodes secured to each of said electrodes substantially at the foci of the opposite electrode to give separated sources of X-rays which radiate in substan tially the same direction.

EUGENE W. CALDWELL.

Witnesses:

HARRY L. DUNCAN, JOHN N. Moonn, 

